Possible Clues:

• Austere city state once, not all in South Africa
• Special area houses drawings depicting ancient city
• Leonidas I led its army
• City-state that battled Athens
• While retreating, an ambush is what gets this ancient city state
• Ambushes set up next to a city long ago
• Greek city-state that was known for its army
• Ancient city where paintings etc shown in spring
• Land of bygone Peloponnesus
• Athens' long-ago foe